gistfile1.js

var async = require('async');
var file = require('file');
var fs = require('fs');
var Q = require('q');

function printAsync(s, cb) {
   var delay = Math.floor((Math.random()*1000)+500);

   setTimeout(function() {
     console.log(s);
     if (cb) cb();
   }, delay);

}

// Q
function qPrintAsync(s) {
  var deferred = Q.defer();

  printAsync(s, function() {
    deferred.resolve();
  });

  return deferred.promise;
}

qPrintAsync(1)
  .then(function () {
    return qPrintAsync(2);
  }).then(function () {
    return qPrintAsync(3);
  }).then(function () {
    return qPrintAsync(4);
  });

// 1
//
printAsync("1", function () {
  printAsync("2", function () {
    printAsync("3");
  });
});

var functions = [];

//
async.waterfall([
  function(cb) {
  },
  function(cb) {
    printAsync("2", cb);
  },
  function(cb) {
    printAsync("3", cb);
  }]);

// 3
//

//var globalCount = 0;

file.walk("/Users/sebcioz/Downloads/PAM08", function (a, dirPath, dirs, files) {
  files.forEach(function (file) {
    var count = 0;

    console.log(file);
    fs.createReadStream(file).on('data', function(chunk) {
      count += chunk.toString('utf8')
      .split(/\r\n|[\n\r\u0085\u2028\u2029]/g)
      .length-1;
    }).on('end', function() {
      console.log(file, count);
      globalCount += count;
    }).on('error', function(err) {
      console.error(err);
    });
  });
});